1. Field of the Invention
The present invention relates to a honeycomb structure, and more particularly, it relates to a honeycomb structure in which an aspect ratio of each end surface is 1.2 or more, and cracks are not easily generated in each joining portion between filters, when a difference in temperature between the inside and the outside of the filter is made.
2. Description of Related Art
Heretofore, a honeycomb structure made of a ceramic material has been used in a catalyst carrier which utilises a catalytic action, a filter which collects a particulate matter in an exhaust gas, especially diesel fine particles (a diesel particulate filter hereinafter abbreviated to “DPF” sometimes), or the like for an internal combustion engine, a boiler, a chemical reaction device, a reformer for a fuel cell, or the like.
The honeycomb structure for use in this purpose usually has a plurality of cells which are defined by porous partition walls and which become through channels of a fluid. When the honeycomb structure is used as the particulate matter collecting filter, plugged portions are arranged in end portions of adjacent cells on opposite sides to form checkered patterns in end surfaces. In a honeycomb structure body having such a structure, a fluid to be treated flows into a cell which is not provided with the plugged portion is an inflow side and surface, i.e., the cell provided with the plugged portion in an outflow side end surface, passes through the porous partition wall, and is discharged from the adjacent cell, i.e., the cell which is provided with the plugged portion in the inflow side end surface and is not provided with the plugged portion in the outflow side end surface. In this case, the partition wall serves as the filter. For example, when the honeycomb structure is used as the DPF, a particulate setter (hereinafter abbreviated, to “PM” sometimes) such as soot discharged; from a diesel engine is collected by the partition walls and deposited on the partition walls.
Such a honeycomb structure is known which is obtained by joining a plurality of honeycomb segments having a honeycomb shape together by a joining material. Specifically, an example of the honeycomb structure is a honeycomb structure including a honeycomb structure section obtained by joining a plurality of honeycomb segments having a honeycomb shape together by a joining material, and an outer peripheral wall forced to cover an outer peripheral surface of this honeycomb structure section (see, e.g., Patent Document 1).